1. Field of the Invention
The present invention relates to a method of distributing information in a wireless network, and more particularly to a technique for reducing the load on a wireless network in sending similar information to a number of nodes.
2. Description of the Related Art
In conventional wireless networks, a number of nodes located in the coverage area send and receive information to and from each other. When a sending node sends information to receiving nodes in a given state (for example, nodes that are moving at a speed of more than 80 km per hour) in such a wireless network, the sending node generally sends the information to each of the receiving nodes by using a unicast protocol, i.e., by specifying the respective addresses of the receiving nodes. However, where there are a large number of receiving nodes in the given state in the wireless network, the above method requires the sending node to repeat sending of the information the number of times corresponding to the number of the receiving nodes in the given state. This may cause increased traffic in the wireless network, thus resulting in increased load on the wireless network.
Multicast protocols (such as DVMRP, MOSPF, and so on) common in wired networks tend to involve a large number of packets for path control and involve long data headers. Therefore, if such a multicast protocol is used for sending and receiving information in a dense wireless network (having one hundred or more nodes in the coverage area), the wireless network may be congested due to the path control packets to have a heavy load. Accordingly, using the multicast protocols cannot solve the above described problem.
Japanese laid-open patent publication 2003-158548 discloses a packet sending/receiving system that achieves flexible and effective multicast when a terminal knows the logical device addresses of all other terminals that can communicate with the terminal itself as well as knowing the logical device address of the terminal itself. However, even with this technique, the above described problem cannot be solved.